bug in UNIXpc phone manager?

[Brant Cheikes]

If you don't use the UNIXpc phone manager, hit 'n' now.

Occasionally I have had the telephone unit connected to my 3b1 ring,
but when I pick up the handset, I get dead silence.  I once thought
that these were crank calls, but then I discovered that on those
occasions, a telephone set on the same line but in a different room
was NOT ringing.  In fact, if I let the computer phone ring, but
picked up the phone in the other room, (a) I'd get a dial tone, and
(b) the computer phone would cease ringing.  I am running UNIX 3.51a,
using the patched phone manager from the fixdisk, and have a two-line
configuration.

I've also noticed that after experiencing the mysterious ringing, if I
pick up the computer handset, (a) the phone manager status line fails
to switch from IDLE to ACTIVE, and (b) I do not get a dial tone.
SHIFT-F2 brings up the call screen normally, and that occasionally
"resets" the phone manager so that it once again recognizes handset
off-hook. Sometimes that's not enough and I have to toggle the line
select.  Toggling line select has so far never failed to get things
working again.

My conclusion is that the phone manager or the machine itself is
somehow generating spurious ringing.  This anomalous behavior happens
only very rarely, e.g., weeks or months apart.  Has anyone else
encountered this behavior?  Is it a known bug?
-- 
Brant Cheikes
University of Pennsylvania, Department of Computer and Information Science
brant at manta.pha.pa.us, brant at linc.cis.upenn.edu, bpa!manta!brant